1. Technical Field
The present disclosure relates to a semiconductor device. More particularly, the present disclosure relates to a nonvolatile memory cell.
2. Description of Related Art
Recently, a nonvolatile semiconductor storage device called resistance random access memory (ReRAM) has received more attention. This storage element is a metal-insulator-metal (MIM) structure formed by sandwiching a so called transition metal oxide (TMO) between a top electrode and a bottom electrode. A ReRAM is used as a memory element via the changing of the element into two states, such as “0” and “1”, depending on the two resistance states, in terms of the low resistance state or high resistance state. A process to change the element from the high resistance state to the low resistance state is called a SET process, and a process of changing from the low resistance state to the high resistance state is called a RESET process. Data can be read by measuring the magnitude of the current flowing through the resistance storage element which represents high current flow (low resistance) or low current (high resistance).
In an ReRAM, to prevent the resistance storage element from being damaged when a large current flows through the element, a diode or transistor or any other suitable device is used to limit the current. On the other hand, in order to scale the memory size, people used different strategies to minimize the storage size, e.g., the cross-bar array with diodes to limit the current. To meet the high current requirements in the forming of the large ReRAM array, diodes, bipolar transistors, or MOSFETs are used for the memory element.